Green Roofs in Uppsala : Potential food yield and thermal insulating effects of a green roof on a building

Abstract: Climate change has caused severe vulnerabilities for the global food production system and alternative agriculture methods are needed as a solution. Urban agriculture (UA) can be a sustainable solution, making the global food system more resilient and increasing the global food security. Using available empty rooftops to implement green roofs for food production can be a solution to challenges faced by urban agriculture, such as unavailability of land and proper amount of sunlight. The aim of this thesis is to explore the potential of green roofs in Uppsala city, looking into the food production capacity and the energy conservation benefits for buildings having a green roof. With the help of GIS software, 745 flat roofs with a total available area of 877408 m2, were considered feasible for implementing green roofs. Upon calculations based on yields obtained from other studies, the results revealed that the annual vegetable production on potential green roofs in Uppsala city is 23550 T of tomato, 48 T of cabbage and 96 T of chilli. On comparing the tomato production with the amount of tomato consumed annually by the population of Uppsala city, the data reveals that less than 10 % of the estimated production can meet the annual demand.Upon investigating the thermal insulation effects of green sedum roof on a building in Uppsala city, the thesis reveals that annually, 824 kWh or .824 MWh can be saved, providing a monetary benefit of SEK 543. The results point out that, on implementation of green sedum roofs on 100 buildings, about 82 MWh amount of energy can be conserved, thus reducing the overall consumption of fuels such as peat and oil and reducing the emissions of green house gases. Green roofs in comparison with conventional roofs can also act as a heat sink to keep the building cooler during warmer summers, thus reducing the demand for artificial cooling. Keywords: Sustainable Development, Urban Sustainability, Food Security, Energy Security, Resilience, Urban Agriculture, Green Roof, Thermal Insulation, Energy Conservation, Climate Change.